Etching apparatus



R. R. ROBERTSON. ETCHING APPARATUS.

APPLICATION FILED MAY 11, 1920.

Patented 001;. H, 1921.."

3 SHEETS-SHEET1.

IN VENTOR I IIIM m l lw Mw m w 7 WITNESS M @MJBXOWM ATTORNEYS R. R. ROBERTSON.

ETCHING APPARATUS.

APPLICATION FILED MAY II, 1920.

Patented 00$. H, 1921..

3 SHEETS-SHEET 2- INV NTOR fizerz flwerajom w A TTOR NE YS APPLICATION FILED MAY [1, 1920- R. R. ROBERTSON.

ETCHING APPARATUS.

Patented 001;. n, 1921.

3 SHEETS-SHEET 3- VQPSIWESS A TTOR NE YS Cit ' to reduce undercutting ot the mea re; l

Sonya citizen of: the United fitates land resident otwBerkeley, "county of Alarneda and Stateoi California, have invented a. certaln newand useful Etching Apparatus,

of which the following 'is aispeciiication.

The invention relates to anrapparatus for etching plates with etching fluid.

An object of the invention is to hrovide an etching apparatuswvhich operates to subject the plate to a uniform etching fluid spray over its entire surface.

Another object of the invention iswto pro vide an etching apparatus which operates plate to a minimum. 1 l

A. further objectot the invention is to provide an etching apparatus which open ates to cause an abundant .flow off-air through the etching chamber.

A further object of the invention is to provide an etchingapparatus in \vhichall parts which may be deleteriously ail-acted by the etching fluidare shielded from contact therewith. i

through one Fig. E is a "The invention possesses other: advantageous features, some of which, 1th the fore. going, will'be set forth at length: in the following description,WhereI shall outline have selectedfor illustration in the drawings accompanyinge present speclfication. In said dra vingsi have vshown OIIHQIHlJOClImGIIt of inyeinvenuse; but 'itis to be understood that 'i do not limit myself i to such. form, since the invention, asset forth intheclaims, maybe en1- I and open ng at 1ts other end 111l10;tl16 chamd her at such depth that etching fluid is not bodied: in". a plurality or forms;

lteferrinlgtosaid drawingsci. Figure l =is a' vertical longitudinal section form of apparatusvoit my invention. 1

vertical transverse sect on taken through one "of :the rotatable sprayers.

,Wlltli the cover removed. l 4 F ig. his a cross sectionof one end of sprayer and the receptacle, showing the driv 11w connection; f: a

ig. his a sectiontaken. ontheline 5-5,

Fig. =3-is plan view otthe acidreceptaele Rigger Fig. 6 is a. perspective Tviexyrkof the 'sprayerhub." n i *Fig; 7: is a: perspectivelvlew oi adrivnig l Specification ef Letters'Patexit; i

and forming part of the provided with a vent conduitlf).

se ame.eeeee seegeas sher, canrronnraf,"

nrcrrins arrzinarnsr i Fig; 8 is an elevation of ,a modified form of apparatus;

lhe apparatus of my invention comprises a receptacle 3, preferably of rectangular shape, made of earthenware or other ma terial, which is proof against the acid or y etching fluidw The receptacle .is prmrided casing to project a fluid spray against the plate. The sprayers are preferably formed as rotary impellera the blades 9 of which dip into the fluid and discharge the fluid a spray gainstthesurtace of the plate. By providing alpluralitv of sprayers spaced apart longitudinally of the compartment,

the fluid particles from the sprayers strike the plate perpendicularly and at. a small angle to the perpendicular, so that undercutting of the plate is reduced to a mini- 111111111. The impellers preferably rotate in opposite directions, indicated on the drawings, but that is not essential to the operation of the apparatus.

The etching operation is greatly Fig. .9 is a section taken on the line 9 9;

PatentedOetji1,192i. eea aamer May-.11f1920t seriaino; 380,522. r

.tated by'tlie presence of an abundant supply of air in the ,etchingchaniber, and I have provided means for. producing afloW of air through the chamber." The end Wall 12 of the receptacle 3 is thickened and is. prok vided with a passage or conduit .13 opening at the top of the? receptacle to the atmosphere thrown out through the passage as the sprayers revolve. The unpeli'el s are constructed and rotated n such 7 manner as to cause a continual inflow of air through the conduit 13 which air is mixed iWith the spray and brought into contact.

withthe plate 6 and theexces's air, spent air and etching fluid fumes, continually dis- 5 charge through the eonduit 15- The recep- The opposite end Wall 14 is itadeis usually provided with a draining aperture, normally closed by the plug l7.

The impellers or Sprayers aremade or a material not deleteriously affected by the etching fluid, such as earthenware, Wood or acid-proof iron and areprovided on their ends with integral hubs 18 which extend into pockets formed in the sides of the receptacle. The receptacle is provided on opposite sides with vertically disposed pockets 19, there being two opposed pockets for each impeller. The lower portion of the pocketis defined by an inner wall 21, having a drain passage 22, connecting the pocket and the receptacle, and an outer wall 23. The inner wall is provided at its upper edge with a semicircular depression or aperture surrounded by semi-circular depression 24L. The pocket is closed, above the inner wall 21, by a sliding gate 25, of acid proof material, which fits in guideways at the sides of the pocket. The gate is provided at its lower end with a semi circular depression or aperture surrounded by a semi-circular depres sion 26. When the gate is in position, the two semi-circular apertures form a circular aperture between the pocket and the interior of the receptacle and the hub 18 extends through this aperture. The semi-circular depressions 24 and 26 form a circular seat in which the inner flange 27 of the hub is disposed, the flange acting to obstruct the passage of etching fluid through the hub aperture and into the pocket. The inner face of the flange is sunk below the surface of the gate and the inner wall, so that any etching fluid flowing down the gate will not flow into the pocket. The hub is also provided with an outer flange 28 having an undercut face 29 which acts to deflect any leakage fluid backward and away from the metallic collar. The outer wall 23 of the pocket is provided with an aperture 31 axially alined with the aperture in the inner wall, and the collars extend through the apertures 31 and into engagement with the hubs.

The impeller is provided with a longitudinal bore through which a metallic shaft 32 extends, the shaft extending from the hubs and through the apertures in the outer walls of the pockets. The hubs are provided in their ends with semi circular sockets 33,

-partly surrounding the shaft 32, and the shaft is held fixed to the impeller by collars 34 and surrounding the shaft and fixed thereto by set screws 36 and having semicircular extensions 37 fitted into the sockets 33 in the hubs. The collar 34 is provided with grooved or slotted pulleys 38 which are connected together by a belt 39, and a driving belt 41 connected to a suitable source of power, provides the means for driving the impellers.

The receptacle3 is seated on a suitable base or frame 42, preferably formed of wood, and having depressions 4:3 therein in which the lower ends of the pockets are dis posed, thereby positioning the receptacle on the base. The shafts 32 extend from the collars 34 and 35 and are journaled in bearings 44, secured to the base. The collars and hubs are held free from contact with the receptacle, so that the impellers rotate freely in. their bearings and the pockets and the hub flanges prevent contact of the ctrhing fluid with the metallic parts of the apparatus.

By virtue of this construction, the plate is not only subjected to a uniform spray over its entire surface, which strikes the plate approximately perpendicularly, but an abundant supply of air is provided in the etching chamber. Further. all parts which may be deleteriously affected by contact with the etching fluid, are maintained out of contact with the fluid and the construction of the apparatus is such that the parts exposed to the fiuid may be formed of fluid-proof material.

I have found that an impeller having longitudinally extending parallel vanes, smoothly curved alol'ig their inner and outer surface, will prodlrc a uniform spray over the surface of the plate. Each vane is substantially concave-convex in cross section and of gradually increasing thickness from edge to base, forming-g" pockets in which the fluid is picked up and from which it is projected over the edge of the vane as the impeller rotates.

In. Figs. 8 and 9 I have shown a modified form of constru tion which possesses several features of advantage. In this constriu-tion, the receptacle is formed in two parts, comprising an acid proof tray "ill having sen1icircular apertures or depressions 47 formed in the upper edges of the side walls through which the sprayer hubs 18 extend. Seated in or on the tray is a fluid proof housing 43 provided with a cover, means for holding the plate and passages as above described. for providing an abundant flow of air through the receptacle. The housing 43 preferably sits into the tray and is provided on the lower edges of the side walls with elongated apertures having semi-circular upper walls 49. These apertures are wider than the hubs 18 and slip down over the hubs, so that the semi-circular a pertures eooperate to form a circular aperture through which the hub extends. The housing is provided with a depression 51, snrroumling the aperture therein, and the flange. 52 on the hub seats in the depression and overlies the aperture, to prevent the discharge of etching fluid through the aperture. The sprayer is constructed, supported and driven in the same manner as in the construction shown in Fig. 2. In this latter construction. the impeller may be removed by lifting off the housing and opening the hearings or by releasing the collars and sliding out the shaft.

I claim:

1. An etching apparatus comprising a, receptacle adapted to contain a quantity of etching liquid and provided with an air inlet passage extending downwardly into said receptacle and an outlet adjacent the top of the receptacle, means for supporting a plate fresh air through the receptacle;

2. An etching apparatus comprising a receptacle adapted to contain a quantity of etching liquid, an air "inlet passage in one wall,ana1r outlet passage 1n the opposite wall of the receptacle, means for supportmg a plate to be etched in said receptacle, and rotary meansfor discharglng a spray ofetching liquid against said plate, and for maintaining a constant circulation of fresh air through the receptacle at atmospheric pressure. p v

3. Anetching apparatus comprising a receptacle adapted to contain a quantity of etchin fluid, a rotatable sprayer in said receptacl e, hubs on said sprayer, opposite walls of said receptacle being provided with semrcircular apertures, movable walls l1avedges cooperating with said first mentioned apertures to form circular apertures through which said hubs extend, flanges onsaid hubs, said walls being provided with depressions,

surrounding the apertures and in which said flanges are disposed, and means engaging one ofsaid hubs for rotating the sprayer.

4. An etching apparatus comprising a re ceptacle' adapted to contain a quantity of etching fluid having side walls provided 111g semi-circular apertures in the lower any hand.

movable wallhaving a depression in its lower edge cooperating with the inner wall of each pocket, the two cooperating depressions forming an aperture alined with the aperture in the outer wall, a rotatable sprayer in said receptacle, hubs on said sprayer extending through said apertures and flanges on the hubs overlying said apertures. r

. 5. An etching apparatus comprising a receptacle adapted to contain a quantity of etching fluid having side walls provided with double walled pockets, the outer walls of said pockets having. aperturesv therethrough and the inner wall of said pocket terminating in the plane of the center of said aperture and having a semi-circular de pression therein, gates slidably mounted in said receptacle in alinement with the inner pocket walls and having semi-circular apertures cooperating with said first mentioned semi-circular apertures to form circular apertures in alinement with the apertures in the outer walls, a rotatable sprayer in said receptacle, hubs on said sprayer extend ing through said apertures and flanges on said-hubslying on opposite sides of said inner walls.

An etching apparatus comprlslng a receptacle having apertures for the free flow of fresh air through the chamber of the receptacle, means for holding a plate horizontally, face down in the receptacle, and means for continually spraying an active liquid against the face of the plate and circulating fresh air at atmospheric pressure through the chamber.

a In testimony whereof, I have hereunto set ROBERT n. nonnnrson. 

